Test Emacs environment on startup.

Patch by Diego N. Barbato

--- a/telega.el	2020-02-07 17:07:18.549970090 +0100
+++ b/telega.el	2020-02-07 17:10:08.383499765 +0100
@@ -82,6 +82,7 @@
   "Start telegramming.
 If prefix ARG is given, then will not pop to telega root buffer."
   (interactive "P")
+  (telega-test-env t)
   (telega--create-hier)
 
   (unless (telega-server-live-p)
